Separation-based analytical methods, including chromatography, electrophoresis and electrochromatography are useful in determining individual samples in complex mixtures. In chromatography, a sample to be analyzed is introduced into a separation column, which contains a mobile phase and a stationary phase. Components of the sample separate as the sample passes through the column due to differences in interaction of the different components with the stationary phase.
Electrophoresis is a separation technique that is based on the mobility of ions in an electric field. In capillary electrophoresis, a sample is placed in a capillary tube, which contains an electrophoretic medium. Upon application of an electric field across the capillary, components of the sample migrate at different rates towards the oppositely charged ends of the capillary based on their relative electrophoretic mobilities in the medium. Electrochromatography is a combination of chromatography and electrophoresis, in which the mobile phase is transported through the separation system by electroosmotic flow (EOF).
Separation of samples in complex mixtures based on analytical systems that are capable of executing large numbers of separations would be useful. In particular, separation technologies that process multiple samples quickly and multi-dimensional separations for each sample are desired. However, existing separation technologies do not generally have these features. Liquid chromatography systems do not readily adapt to parallel processing because adding multiple precision pumps and valves, necessary to deliver multiple samples, is both impractical and expensive. Multi-dimensional chromatography separations are feasible by transferring components from a first separation column to a second separation column with rotary valves. However, such processes can be very slow. Parallel processing for capillary electrophoresis has been achieved using microfabrication, which allows multiple channels to be placed on a single chip. However, a limitation is that no methods are available to introduce a large number of samples into the channels and to rapidly clean the sample metering channels between separations.
The present invention relates to separation columns for use in chromatography, electrochromatography and electrophoresis, which overcome the sample limitations of the existing separation systems. The separation columns of the present invention also require orders of magnitude less solvent and analyte, thereby diminishing the sample disposal problem.